Antifoggants for photographic silver halide emulsions



carboxylic acids.

United States Patent() 3,128,137 ANTIFOGGANTS FDR PHOTOGRAPHIC SILVER HALIDE EMULSIONS John Sagal, in, Mount Frospect, Ill., and Frank D. Allen,

Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Feb. 8, 1961, Ser. No. 87,752 8 Claims. (Cl. 96-109) This invention relates to photography, and more particularly, to photographic silver halide emulsions which have been stabilized by (treatment with various fog-inhibiting agents or stabilizing compounds.

It is well known that photographic emulsions on storage tend to lose sensitivity and to become spontaneously developable without exposure to light. There is normally a detectable amount of the silver salt reduced during development in the areas where no exposure was given; this is commonly called fog, and sometimes called chemical fog where it is necessary to distinguish between it and the effects of accidental exposure to radiation; in this invention, we are not concerned with the latter.

Fog depends both on the emulsion and the conditions of development; for a given emulsion it increases with the degree of development. With constant development conditions, it tends to increase with time, temperature and relative humidity of storage conditions; it is common practice to make accelerated tests of the stability of photographic emulsions by storage at increased temperature or humidity, or both. It is, of course, desirable to have emulsions as stable as possible under the conditions of high temperature and humidity which may occur in tropical climates, for example. Fog usually appears over the Whole area of the sensitive coating, but when severe, it frequently is non-uniform. Fog may also be caused by exposure to chemicals, for example, hydrogen sulfide and other reactive sulfur compounds, hydrogen peroxide vapor, and strongly reducing materials. While antifoggants and stabilizers may protect, to some extent, against such effects, it is normally understood that an antifoggant protects against spontaneous growth of fog during prolonged storage or storage at high temperatures and humidities, or during development to maximum contrast and speed, or both.

It is, therefore, an object of our invention to provide a method of stabilizing photographic silver halide emulsions. Another object is to maintain the sensitivity and fog levels of photographic silver halide emulsions at or close to initial optimum values under adverse keeping or stonage conditions of high temperatures and humidities. Still another object is to provide stabilizing or antifoggant compounds which are more useful than many of the previously employed stabilizing compounds to which they are structurally related. Other objects will become apparent from a consideration of the following description and examples.

According to our invention, we have found that photographic silver halide emulsions can be stabilized by incorporating therein various carboxylic acids, or watersoluble salts thereof. These carboxylic acids and their salts are aliphatic in structure and contain one or more chlorine or bromine atoms. The bromine-substituted a-l-iphatic carboxylic acids have been found to be especially useful in our invention, and particularly outstanding results have been obtained where a single bromine atom is attached to a carbon atom adjacent to a carboxyl radical.

The chlorineor bromine-substituted aliphatic carboxylic "acids (and water-soluble salts) useful in our invention comprise many of the well known monoand poly- Useful stabilizing compounds according to our invention include brominated or chlorinated 3,128,17 Patented Apr. 7, 1964 ICC derivatives of aliphatic carboxylic acids, such as acetic acid, propionic acid, butyric acid, valeric acid, etc., as well as polycarboxylic acids, such as succinic acid, adipic acid, pimelic acid, etc. These acids can be used in the form of the free acid, or in the form of Water-soluble salts thereof. These acids, or their water-soluble salts, can contain one or more chlorine or bromine atoms. Advantageously, these acids or their water-soluble salts contain no more than one chlorine or bromine atom on a single carbon atom, although acids and water-soluble salts, which contain several chlorine or bromine atoms on different carbon atoms, have been found to be quite useful in our invention. The stabilizing agents which have been found to be of particular utility in our invention contain chlorine and/ or bromine atoms, carbon atoms, hydrogen atoms, and oxygen atoms, and in the case of water-soluble salts, an alkali metal atom, such as sodium or potassium, -or an ammonium radical, such as ammonium, triethanol ammonium, pyridinium, etc,

Typical carboxylic acids useful in practicing our invention include, for example, the following acids (as well as their water-soluble salts, including sodium, potassium, ammonium, pyridinium, t'riethanol ammonium, triethylammonium, etc): bromoacetic acid, uJi-dibromobutyric acid, fi-bromopropi-onic acid, B-chloropropionic acid, 0t,0tdibromoadipic acid, u,a-dibromopimelic acid, oz,a'-dibromosebacic acid, a,a'-dichloroadipic acid, a,ot'-dil)IOI110- succinic acid, or,a-dichloroadipic acid, a,a-bis(bromomethyl)-B bromopropionic acid, a,a-bis(chloron1ethyl)-5- bromopropionic acid, etc.

The photographic silver halide emulsions can be stabilized by adding thereto an aqueous solution, or a solution in a polar solvent (e.g., acetone, pyridine, ethanol, etc.), of the stabilizing compound. Where the free acid is not sufficiently soluble in water, a water-soluble salt thereof can be employed. The amount of stabilizing compound used in our invention can be varied, depending upon the particular emulsion, molecular weight of the stabilized compound, etc. In general, we have found that from about 0.1 to about 10.0 grams of stabilizing compound per mole of silver halide can be employed. The

stabilizing material can be added to an emulsion which has a pH on the acidic side, or the stabilizing compound can be added to an emulsion which has a basic pH. It is sometimes advisable to adjust the pH of the emulsion after addition of the solution of the stabilizing compound to bring the pH to an approximately neutral condition, i.e., a pH of about 6-8.

It is known that various unsaturated, halogen-substituted aldehydes, which also contain a carboxyl group,

such as mucochloric or mncobromic acid, can be emwas separately treated with a quantity of stabilizing compound in the amount shown in the tables. One batch of emulsion was not treated and this particular batch served as a control. The separate batches of emulsion were then coated on an ordinary photographic support, such as a cellulose acetate support, and the coatings dried. The dried coatings were then exposed on an Eastman lb Sensitometer with tungsten illumination and developed for 5 minutes in Kodak Developer DK50 at 68 F. with 3 good agitation. The developed coatings were then fixed, washed and dried, and the speed and fog of the coatings determined. Separate coatings were then incubated for one week at 120 F. and the incubated strips, or coatings, processed in exactly the same manner as the fresh coatings. The relative speeds and fog for each of the coatings are given in the tables. The relative speeds are inversely proportioned to the exposures required to produce a developed density of 0.3 above fog. The DK50 Developer has the following formula:

Grams N-methyl-p-aminphen0l sulfate 2.5 Hydroquinone 2.5 Sodium sulfite (desiccated) 30.0 Sodium metaborate 1 0.0 Potassium bromide 0.5 Water to make 1 liter.

TABLE 1 Fresh Coating incubated Coating Addenda g./mol.

AgX

Relative Fog Relative Fog Speed Speed 100 .10 9o .30 100 .11 102 .11 01 100 .13 74 .29 a, d-dibromopimelic acid... 0. 75 81 .12 69 .16 D0 1.5 85 .09 74 .13 Control 1. 100 13 82 21 a, B-dibromobutyric acid. 1. 98 1 1 72 13 The data outlined in the following table were obtained in the same manner as those of Table I above.

4.- Patent 1,574,944, issued March 2, 1926; Sheppard et a1. U.S. Patent 1,623,499, issued April 5, 1927, and Sheppard et al. U.S. Patent 2,410,689, issued November 5, 1946.

The emulsions can also be treated with salts of the noble metals such as ruthenium, rhodium, palladium, iridium, and platinum. Representative compounds are ammonium chloropalladate, potassium chloroplatinate, and sodium chloropalladite, which are used for sensitizing in amounts below that which produces any substantial fog inhibition, as described in Smith and Trivelli U.S. Patent 2,448,060, issued August 31, 1948.

The emulsions can also be chemically sensitized with gold salts as described in Waller et al. U.S. Patent 2,399,083, issued April 23, 1946, and Damschroder et a1. U.S. Patent 2,642,361, issued June 16, 1953. Suitable compounds are potassium chloroaurite, potassium aurithiocyanate, potassium chloroaurate, auric trichloride and Z-aurosulfobenzothiazole methochloride.

The emulsions can also be chemically sensitized with reducing agents such as stannous salts (Carroll U.S. Patent 2,487,850, issued November 15, 1949), polyamines, such as diethylene triarnine (Lowe and Jones U.S. Pat ent 2,518,698, issued August 15, 1950), polyamines, such as spermine (Lowe and Allen U.S. Patent 2,521,925, issued September 12, 1950), or bis(f3-aminoethyl)sulfide and its water-soluble salts (Lowe and Jones U.S. Patent 2,521,926, issued September 12, 1950).

The emulsions can also be optically sensitized with cyanine and merocyanine dyes, such as those described in Brooker U.S. Patents 1,846,301, issued February 23, 1932; 1,846,302, issued February 23, 1932; and 1,942,854, issued January 9, 1934; White U.S. Patent 1,990,507, is-

TABLE 11 Fresh Coatings Incubated Coatings g./mol. Addenda AgX Relative Gamma Fog Relative Gamma Fog Speed Speed Control. 100 1. 23 12 73 1.02 .28 Mucobromic acid 1. 5 91 1.17 .10 39 73 Do 3.0 82 1.10 .11 35 .72 .85 a, a-dibromoadipic acid" 1. 5 102 1. 25 .11 83 1.10 13 Do 3.0 97 1. 22 11 1.12 12 a, adib101'I10SllcciIli0 ac 1. 5 97 1. 22 12 78 1.08 15 o 3.0 102 1. 25 .11 78 1.07 .11 Control.-- 100 1.30 12 89 1.11 .19 a, a-dichloroadipic acid 6.0 102 1.25 10 1.08 13 fi-bromopropionic acid 3.0 78 1.19 14 80 1.17 13 Control- 100 1.18 10 52 80 61 1, S-dibromosebacio acid 3.0 102 1. 22 10 52 78 13 00111101-. 100 1. 18 .10 105 1.05 21 2, 2-bis(bromomethyl)-3-brornopropionic acid. 0. 3 97 1. 23 10 97 1. 15 l5 2, 2-bis(chloromethyl)-3-bromopr0pi0nic acid. 0.3 1. 25 10 1.17 .13 ontrol 100 1.30 12 89 1. 11 19 a, a-dichloroadipic acid 3.0 94 1. 36 10 100 1. 24 10 6.0 89 1. 51 .08 94 1. 20 09 B-chloropropionic acid- 3.0 102 1. 43 .08 102 1. 42 12 Do 6.0 91. 1.38 08 95 1. 28 .09 Iodoacetic acid 3.0 38 94 .07 T00 slow to read .08

Table II shows that the stabilizing agents of our invention are quite eifective, particularly upon storage under adverse keeping conditions. Under identical conditions, the structurally related mucobromic acid has desensitizing properties and affords no beneficial stabilizing properties. The above Table II also shows that the nature of the halogen atoms has a profound eifect upon the antifoggant and stabilizing efficiency of aliphatic carboxylic acids. Note the strong desensitizing eiiect of iodoacetic acid which is not a member of the class of materials used in our invention.

The photographic emulsions used in practicing our invention are of the developing-out type.

The emulsions can be chemically sensitized by any of the accepted procedures. The emulsions can be digested with naturally active gelatin, or sulfur compounds can be added such as those described in Sheppard U.S.

sued February 12, 1935; Brooker and White U.S. Patents 2,112,140, issued March 22, 1938; 2,165,338, issued July 11, 1939; 2,493,747, issued January 10, 1950; and 2,739,964, issued March 27, 1956; Brooker and Keyes U.S. Patent 2,493,748, issued January 10, 1950; Sprague U.S. Patents 2,503,776, issued April 11, 1950, and 2,519,001, issued August 15, 1950; Heseltine and Brooker U.S. Patent 2,666,761, issued January 19, 1954; Heseltine U.S. Patent 2,734,900, issued February 14, 1956; Van Lare U.S. Patent 2,739,149, issued March 20, 1956; and Kodak Limited British Patent 450,958, accepted July 15, 1936.

The emulsions may also contain speed increasing compounds of the quaternary ammonium type of Carroll U.S. Patent 2,271,623, issued February 3, 1942; Carroll and Allen U.S. Patent 2,288,226, issued June 30, 1942; and Carroll and Spence U.S. Patent 2,334,864, issued Novemr. ber 23, 1943; or the polyethylene glycol type of Carroll and Beach U.S. Patent 2,708,162, issued May 10, 1955; or the quaternary ammonium salts and polyethylene glycols of Piper U.S. Patent 2,886,437, issued May 12, 1959; as well as the thiopolymers of Graham and Sagal U.S. application Serial No. 779,839, filed December 12, 1958 (now U.S. Patent 3,046,129, issued July 24, 1962), and the Dann and Chechak U.S. application Serial No. 779,874, filed December 12, 1958 (now U.S. Patent 3,046,134, issued July 24, 1962).

The emulsions may contain a suitable gelatin plasticizer such as glycerin; a dihydroxy alkane such as 1,5-pentane diol as described in Milton and Murray U.S. Patent 2,960,404, issued November 15, 1960; an ester of an ethylene bis-glycolic acid such as ethylene bis(methyl glycolate) as described in Milton U.S. Patent 2,904,434, issued September 15, 1959; bis-(ethoxy diethylene glycol) succinate as described in Gray U.S. Patent 2,940,854, issued June 14, 1960, or a polymeric hydrosol as results from the emulsion polymerization of a mixture of an amide of an acid of the acrylic acid series, an acrylic acid ester and a styrene-type compound as described in Tong U.S. Patent 2,852,386, issued September 16, 1958. The plasticizer may be added to the emulsion before or after the addition of a sensitizing dye, if used.

The emulsions may be hardened with any suitable hardener for gelatin such as formaldehyde; a halogensubstituted aldehyde containing a carboxyl group, such as mucobromic acid as described in White U.S. Patent 2,080,019, issued May 11, 1937; a compound having a plurality of acid anhydride groups such as 7,8-diphenylbicyclo (2,2,2)-7-octene-2,3,5,6-tetra-carboxylic dianhydride, or a dicarboxylic or a disulfonic acid chloride such as terephthaloyl chloride as described in Allen and Carroll U.S. Patents 2,725,294 and 2,725,295, both issued November 29, 1955; a cyclic 1,2-diketone such as cyclopentane-LZ-dione as described in Allen and Byers U.S. Patent 2,725,305, issued November 29, 1955; a bisester of methane-sulfonic acid such as 1,2-di-(methanesulfonoxy)-ethane as described in Allen and Laakso U.S. Patent 2,726,162, issued December 6, 1955; 1,3-dihydroxymethylbenzimidazol-2-one as described in July, Knott and Pollak U.S. Patent 2,732,316, issued January 24, 1956; a dialdehyde or a sodium bisulfide derivative thereof, such as ,B-methyl glutaraldehyde bis-sodium bisulfide as described in Allen and Burness Canadian Patent 588,451, issued December 8, 1959; a bis-aziridine carboxamide such as trimethylene bis(1-aziridine carboxamide) as described in Allen and Webster U.S. Patent 2,950,197, issued August 23, 1960; 2,3-dihydroxy dioxane as described in Jelireys U.S. Patent 2,870,013, issued January 20, 1959; or bisisocyanate as described in Henn et al. U.S. patent application Serial No. 805,357, filed April 10, 1959.

The emulsions may contain a coating aid such as saponin; a lauryl or oleyl monoether of polyethylene glycol as described in Knox and Davis U.S. Patent 2,831,766, issued April 22, 1958; a salt of a sulfated and alkylated polyethylene glycol ether as described in Knox and Davis U.S. Patent 2,719,087, issued September 27, 1955; an acylated alkyl taurine such as the sodium salt of N-oleoyl-N-methyl taurine as described in Knox, Twardokus and Davis U.S. Patent 2,739,891, issued March 27, 1956; the reaction product of a dianhydride of tetracarboxybutane with an alcohol or an aliphatic amine containing from 8 to 18 carbon atoms which is treated with a base, for example, the sodium salt of the monoester of tetracarboxybutane as described in Knox, Stenberg and Wilson U.S. Patent 2,843,487, issued July 15, 1958; a Water-soluble maleopimarate as described in Knox and Fowler U.S. Patent 2,823,123, issued February 11, 1958; an alkali metal salt of a substituted amino acid such as disodium N-(carbo-p-tert.octylphenoxypentaethoxy)-glutamate as described in Knox and Wilson U.S. patent application Serial No. 600,679, filed July 30, 1956 (now U.S. Patent 3,038,804, issued July 12, 1962); or a sulfosuccinarnate such as tetrasodium N-(l,2-dicarboxyethyl)-N-octadecyl sulfosuccinamate as described in Knox and Stenberg U.S. patent application Serial No. 691,125, filed October 21, 1957 (now U.S. Patent 2,992,108, issued July 11, 1961), or a sodium salt of an alkylarylpolyether sulfonate of Baldsiefen U.S. Patent 2,600,831, issued June 17, 1952.

The addenda which we have described may be used in various kinds of photographic emulsions. In addition to being useful in X-ray and other nonoptically sensitized emulsions they may also be used in orthocromatic, pan chromatic, and infrared sensitive emulsions. They may be added to the emulsion before or after any sensitizing dyes which are used. Various silver salts may be used as the sensitive salt such as silver bromide, silver iodide, silver chloride, or mixed silver halides such as silver chlorobromide or silver brornoiodide. The agents may be used in emulsions intended for color photography, for example, emulsions containing color-forming couplers or emulsions to be developed by solutions containing couplers or other color-generating materials, emulsions of the mixed-packet type, such as described in Godowsky U.S. Patent 2,698,794, issued January 4, 1955; or emulsions of the mixed-grain type, such as described in Carroll and Hanson U.S. Patent 2,592,243, issued April 8, 1952. These agents can also be used in emulsions which form latent images predominantly on the surface of the silver halide crystal or in emulsions which form latent images predominantly inside the silver halide crystal, such as those described in Davey and Knott U.S. Patent 2,592,250, issued April 8, 1952.

These may also be used in emulsions intended for use in diffusion transfer processes which utilize the undeveloped silver halide in the nonimage areas of the negative to form a positive by dissolving the undeveloped silver halide and precipitating it on a receiving layer in close proximity to the original silver halide emulsion layer. Such processes are described in Rott U.S. Patent 2,352,- 014, issued June 20, 1944, and Land U.S. Patents 2,584,- 029, issued January 29, 1952; 2,698,236, issued December 28, 1954 and 2,543,181, issued February 27, 1951; and Yackel et a1. U.S. patent application Serial No. 586,705, filed May 23, 1956 (now U.S. Patent 3,020,155, issued February 6, 1962). They may also be used in color transfer processes which utilize the diflusion transfer of an image-wise distribution of developer, coupler or dye, from a light-sensitive layer to a second layer, while the two layers are in close proximity to one another. Color processes of this type are described in Land US. Patents 2,559,643, issued July 10, 1951, and 2,698,798, issued January 4, 1955; Land and Rogers Belgian Patents 554,933 and 554,934, granted August 12, 1957; International Polaroid Belgian Patents 554,212, granted July 16, 1957, and 554,935, granted August 12, 1957; Yutzy U.S. Patent 2,756,142, granted July 24, 1956 and Whitmore and Mader U.S. patent application Serial No. 734,141, filed May 9, 8. They may also be used in emulsions intended for use in a monobath process such as described in Haist et al. U.S. Patent 2,875,048, issued February 24, 1959, and in web-type processes, such as the one described in Tregillus et al. U.S. patent application Serial No. 835,473, filed August 24, 1959.

In the preparation of the silver halide dispersions employed for preparing silver halide emulsions, there may be employed as the dispersing agent for the silver halide in its preparation, gelatin or some other colloidal material such as colloidal albumin, a cellulose derivative or a synthetic resin, for instance, a polyvinyl compound. Some colloids which may be used are polyvinyl alcohol or a hydrolyzed polyvinyl acetate as described in Lowe U.S. Patent 2,286,215, issued June 16, 1942; a far hydrolyzed cellulose ester such as cellulose acetate hydrolyzed to an acetyl content of 1926% as described in U.S. Patent 2,327,808 of Lowe and Clark, issued August 24, 1943; a

water-soluble ethanolamine cellulose acetate as described in Yutzy US. Patent 2,322,085, issued June 15, 1943; a polyacrylamide or an imidized polyacrylamide as described in Lowe, Minsk and Kenyon U.S. Patent 2,541,- 474, issued February 13, 1951; zein as described in Lowe US. Patent 2,563,791, issued August 7, 1951; a vinyl alcohol polymer containing urethane carboxylic acid groups of the type described in Unruh and Smith US. Patent 2,768,154, issued October 23, 1956; or containing cyanoacetyl groups such as the vinyl alcohol-vinyl cyanoacetate copolymer as described in Unruh, Smith and Priest US. Patent 2,808,331, issued October 1, 1957; or a polymeric material which results from polymerizing a protein or a saturated acylated protein with a monomer having a vinyl group as described in US Patent 2,852,382, of Illingsworth, Dann and Gates, issued September 16, 1958.

If desired, compatible mixtures of two or more of these colloids may be employed for dispersing the silver halide in its preparation. Combinations of these antifoggants, sensitizers, hardeners, etc., may be used.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

What we claim as our invention and desire secured by Letters Patent of the United States of America is:

1. A photographic gelatino-silver-halide emulsion stabilized by the addition thereto of a saturated aliphatic carboxylic acid containing from 2 to 10 carbon atoms and having a bromine atom substituted on a carbon atom adjacent to the carboxyl radical.

2. A photographic gelatino-silver halide emulsion stabilized by the addition thereto of a water-soluble salt of a saturated aliphatic carboxylic acid containing from 2 to 10 carbon atoms and having a bromine atom substituted on a carbon atom adjacent to the carboxyl radical.

3. A photographic gelatino-silver halide emulsion stabilized by the addition thereto of a saturated aliphatic dicarboxylic acid containing from 4 to 10 carbon atoms and having a bromine atom substituted on a carbon atom adjacent to a carboxyl radical.

4. A photographic gelatino-silver-halide emulsion stabilized by the addition thereto of a water-soluble salt of a saturated aliphatic dicarboxylic acid containing from 4 to 10 carbon atoms and having a bromine atom substituted on a carbon atom adjacent to a carboxyl radical.

5. A photographic silver halide emulsion stabilized by the addition thereto of a,a'-dibromosuccinic acid.

6. A photographic silver halide emulsion stabilized by the addition thereto of a,a'-dibromoadipic acid.

7. A photographic silver halide emulsion stabilized by the addition thereto of a,B-dibromobutyric acid.

8. A photographic silver halide emulsion stabilized by the addition thereto of u,a'-dibromopimelic acid.

References Cited in the file of this patent UNITED STATES PATENTS 2,438,716 Mueller Mar. 30, 1948 OTHER REFERENCES Glafkides: Photographic Chemistry, 1, Fountain Press, London, 1958, pages 374-78. 

1. A PHOTOGRAPHIC GELATINO-SILVER HALIDE EMULSION STABILIZED BY THE ADDITION THERETO OF A SATURATED ALIPHATIC CARBOXYLIC ACID CONTAINING FROM 2 TO 10 CARBON ATOMS AND HAVING A BROMINE ATOM SUBSTITUTED ON A CARBON ATOM ADJACENT TO THE CARBOXYL RADICAL. 